Inductive coil ignition systems for engines, in particular motor vehicle engines, are known. The ignition coil used in such systems has a primary winding which is periodically acted upon by a primary current. This current serves to build up in the coil a magnetic field which is intended to serve as an energy reservoir. At the desired moment of ignition, the primary current is interrupted. The energy stored in the magnetic field then produces a steep rise in the voltage at the secondary winding, resulting in a spark discharge in the spark plug and a correspondingly steep rise in the secondary current. The magnetic energy stored in the coil flows out continuously into the sparks as electrical energy.
In modern ignition systems, there is now a requirement to measure combustion-related parameters as accurately as possible, and to optimize ignition on the basis of them. One method, known from the existing art, for determining such combustion parameters is represented by the ionization current measurement method.
Since the ionization current measurement method requires an extinguished ignition spark, it cannot be used in known ignition systems in which the secondary current decays slowly. Other, more complex measurement systems are instead required in order to detect, for example, incipient knocking in an engine.